package com.chen.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//操作数据库的公共类
public class BaseDao {
    private  static  String driver;
    private  static  String url;
    private  static  String username;
    private  static  String password;

    static {
        Properties  properties = new Properties();
        //通过类加载器读取对应的资源
        InputStream inputStream = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");

        try {
            properties.load(inputStream);
        } catch (IOException ioException) {
            ioException.printStackTrace();
        }

        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");

    }

    //获取数据库的连接
    public static Connection getConnection(){
        Connection connection = null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }

    //编写查询公共类
    public static ResultSet execute(Connection connection,String sql,Object[] params) throws SQLException {
        PreparedStatement statement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            //setObject占位符从1开始，但是数组是从0开始
            statement.setObject(i+1,params[i]);
        }
        return statement.executeQuery();

    }


//    //编写增删改公共方法
//    public static int execute(Connection connection,String sql,Object[] params){
//
//    }

    //释放资源
    public static boolean closeResource(Connection connection,PreparedStatement statement,ResultSet set){
        boolean flag = true;
        if (set!=null){
            try {
                set.close();
                set = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag =false;
            }
        }

        if (connection!=null){
            try {
                connection.close();
                connection = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag =false;
            }
        }

        if (statement!=null){
            try {
                statement.close();
                statement=null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag =false;
            }
        }
        return flag;
    }
}
